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sock_diag: allow concurrent operation in sock_diag_rcv_msg()

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[ Upstream commit 86e8921df05c6e9423ab74ab8d41022775d8b83a ]

TCPDIAG_GETSOCK and DCCPDIAG_GETSOCK diag are serialized
on sock_diag_table_mutex.

This is to make sure inet_diag module is not unloaded
while diag was ongoing.

It is time to get rid of this mutex and use RCU protection,
allowing full parallelism.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Stable-dep-of: eb02688c5c45 ("ipv6: release nexthop on device removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet 2024-01-22 11:26:01 +00:00 committed by Greg Kroah-Hartman
parent 916551244a
commit adf8650938
3 changed files with 40 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/sock_diag.h
View File

@ -23,8 +23,13 @@ struct sock_diag_handler {
int sock_diag_register(const struct sock_diag_handler *h); int sock_diag_register(const struct sock_diag_handler *h);
void sock_diag_unregister(const struct sock_diag_handler *h); void sock_diag_unregister(const struct sock_diag_handler *h);
void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh)); struct sock_diag_inet_compat {
void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh)); struct module *owner;
int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh);
};
void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr);
void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr);
u64 __sock_gen_cookie(struct sock *sk); u64 __sock_gen_cookie(struct sock *sk);

43
net/core/sock_diag.c
View File

@ -17,8 +17,9 @@
#include <linux/sock_diag.h> #include <linux/sock_diag.h>
static const struct sock_diag_handler __rcu *sock_diag_handlers[AF_MAX]; static const struct sock_diag_handler __rcu *sock_diag_handlers[AF_MAX];
static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);
static DEFINE_MUTEX(sock_diag_table_mutex); static struct sock_diag_inet_compat __rcu *inet_rcv_compat;
static struct workqueue_struct *broadcast_wq; static struct workqueue_struct *broadcast_wq;
DEFINE_COOKIE(sock_cookie); DEFINE_COOKIE(sock_cookie);
@ -181,19 +182,20 @@ void sock_diag_broadcast_destroy(struct sock *sk)
queue_work(broadcast_wq, &bsk->work); queue_work(broadcast_wq, &bsk->work);
} }
void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh)) void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr)
{ {
mutex_lock(&sock_diag_table_mutex); xchg((__force const struct sock_diag_inet_compat **)&inet_rcv_compat,
inet_rcv_compat = fn; ptr);
mutex_unlock(&sock_diag_table_mutex);
} }
EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat); EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);
void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh)) void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr)
{ {
mutex_lock(&sock_diag_table_mutex); const struct sock_diag_inet_compat *old;
inet_rcv_compat = NULL;
mutex_unlock(&sock_diag_table_mutex); old = xchg((__force const struct sock_diag_inet_compat **)&inet_rcv_compat,
NULL);
WARN_ON_ONCE(old != ptr);
} }
EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat); EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);
@ -256,20 +258,27 @@ static int __sock_diag_cmd(struct sk_buff *skb, struct nlmsghdr *nlh)
static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack) struct netlink_ext_ack *extack)
{ {
const struct sock_diag_inet_compat *ptr;
int ret; int ret;
switch (nlh->nlmsg_type) { switch (nlh->nlmsg_type) {
case TCPDIAG_GETSOCK: case TCPDIAG_GETSOCK:
case DCCPDIAG_GETSOCK: case DCCPDIAG_GETSOCK:
if (inet_rcv_compat == NULL)
if (!rcu_access_pointer(inet_rcv_compat))
sock_load_diag_module(AF_INET, 0); sock_load_diag_module(AF_INET, 0);
mutex_lock(&sock_diag_table_mutex); rcu_read_lock();
if (inet_rcv_compat != NULL) ptr = rcu_dereference(inet_rcv_compat);
ret = inet_rcv_compat(skb, nlh); if (ptr && !try_module_get(ptr->owner))
else ptr = NULL;
ret = -EOPNOTSUPP; rcu_read_unlock();
mutex_unlock(&sock_diag_table_mutex);
ret = -EOPNOTSUPP;
if (ptr) {
ret = ptr->fn(skb, nlh);
module_put(ptr->owner);
}
return ret; return ret;
case SOCK_DIAG_BY_FAMILY: case SOCK_DIAG_BY_FAMILY:

9
net/ipv4/inet_diag.c
View File

@ -1445,6 +1445,11 @@ void inet_diag_unregister(const struct inet_diag_handler *h)
} }
EXPORT_SYMBOL_GPL(inet_diag_unregister); EXPORT_SYMBOL_GPL(inet_diag_unregister);
static const struct sock_diag_inet_compat inet_diag_compat = {
.owner = THIS_MODULE,
.fn = inet_diag_rcv_msg_compat,
};
static int __init inet_diag_init(void) static int __init inet_diag_init(void)
{ {
const int inet_diag_table_size = (IPPROTO_MAX * const int inet_diag_table_size = (IPPROTO_MAX *
@ -1463,7 +1468,7 @@ static int __init inet_diag_init(void)
if (err) if (err)
goto out_free_inet; goto out_free_inet;
sock_diag_register_inet_compat(inet_diag_rcv_msg_compat); sock_diag_register_inet_compat(&inet_diag_compat);
out: out:
return err; return err;
@ -1478,7 +1483,7 @@ static void __exit inet_diag_exit(void)
{ {
sock_diag_unregister(&inet6_diag_handler); sock_diag_unregister(&inet6_diag_handler);
sock_diag_unregister(&inet_diag_handler); sock_diag_unregister(&inet_diag_handler);
sock_diag_unregister_inet_compat(inet_diag_rcv_msg_compat); sock_diag_unregister_inet_compat(&inet_diag_compat);
kfree(inet_diag_table); kfree(inet_diag_table);
} }